This 45-foot Whale Shark may look ferocious, but its actually harmless to humans. This particular shark was caught in Florida in 1912, then mounted to be shown in New York and later Atlantic City. A living Whale Shark also poses little threat. Marine biologists studying them swim with Whale Sharks in the open seas. Staying with them can be tricky, though, because they are capable of diving very deepover a mile down. In the depths of the ocean, they feed chiefly on small marine life such as plankton that is filtered in its mouth when suctioning water like a vacuum cleaner suctions air. Although this fish is as big as a whale, its definitely a shark. This is because its skeleton is made of cartilage, not bone. Unlike most sharks that have pointed or angular heads, the Whale Shark has a blunt head.

An Unprecedented Aggregation of Whale Sharks, Rhincodon typus, in Mexican Coastal Waters of the Caribbean Sea

Author:

Tyminski, John

Hueter, Robert

de la Parra Venegas, Rafael

Gregorio Remolina, Jose

Gonzalez Cano, Jaime

Weigt, Lee A.

Carlson, Bruce

Ormos, Andrea

Maslanka, Michael

Dove, Alistair

Object Type:

Smithsonian staff publication

Electronic document

Year:

2011

Abstract:

Whale sharks, Rhincodon typus, are often perceived as solitary behemoths that live and feed in the open ocean. To the contrary, evidence is accumulating that they are gregarious and form seasonal aggregations in some coastal waters. One such aggregation occurs annually north of Cabo Catoche, off Isla Holbox on the Yucatan Peninsula of Mexico. Here we report a second, much denser aggregation of whale sharks (dubbed "the Afuera") that occurs east of the tip of the Yucatan Peninsula in the Caribbean Sea. The 2009 Afuera event comprised the largest aggregation of whale sharks ever reported, with up to 420 whale sharks observed in a single aerial survey, all gathered in an elliptical patch of ocean approximately 18 km(2). Plankton studies indicated that the sharks were feeding on dense homogenous patches of fish eggs, which DNA barcoding analysis identified as belonging to little tunny, Euthynnus alletteratus. This contrasts with the annual Cabo Catoche aggregation nearby, where prey consists mostly of copepods and sergestid shrimp. Increased sightings at the Afuera coincide with decreased sightings at Cabo Catoche, and both groups have the same sex ratio, implying that the same animals are likely involved in both aggregations; tagging data support this idea. With two whale shark aggregation areas, high coastal productivity and a previously-unknown scombrid spawning ground, the northeastern Yucatan marine region is a critical habitat that deserves more concerted conservation efforts.